Bump libxml2 to v2.15.3

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e05ff19..6871f0c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@
 * Update aom.cmd/LocalAom.cmake: v3.14.1
 * Update LocalAvm.cmake: research-v15.0.0
 * Update libjpeg.cmd/LocalJpeg.cmake: 3.1.4.1
+* Update libxml2.cmd/LocalLibXml2.cmake: v2.15.3
 * Update svt.cmd/svt.sh/LocalSvt.cmake: v4.1.0
 * Update zlibpng.cmd/LocalZlibpng.cmake: libpng 1.6.58
 * Fix decoding layered image with multiple scaled alpha layers

cmake/Modules/LocalLibXml2.cmake

diff --git a/cmake/Modules/LocalLibXml2.cmake b/cmake/Modules/LocalLibXml2.cmake
index 9d2f334..e83482f 100644
--- a/cmake/Modules/LocalLibXml2.cmake
+++ b/cmake/Modules/LocalLibXml2.cmake
@@ -1,4 +1,4 @@
-set(AVIF_LIBXML_GIT_TAG "v2.15.2")
+set(AVIF_LIBXML_GIT_TAG "v2.15.3")
 
 # First, whether the library exists.
 set(PREFIXES lib ${AVIF_LIBRARY_PREFIX})

ext/libxml2.cmd

diff --git a/ext/libxml2.cmd b/ext/libxml2.cmd
index 088853e..7245cff 100755
--- a/ext/libxml2.cmd
+++ b/ext/libxml2.cmd
@@ -5,7 +5,7 @@
 
 : # libxml2 is released under the MIT License.
 
-git clone -b v2.15.2 --depth 1 https://github.com/GNOME/libxml2.git
+git clone -b v2.15.3 --depth 1 https://github.com/GNOME/libxml2.git
 
 cmake -G Ninja -S libxml2 -B libxml2/build.libavif/ -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=libxml2/install.libavif -DLIBXML2_WITH_ICONV=OFF -DLIBXML2_WITH_PROGRAMS=OFF -DLIBXML2_WITH_PYTHON=OFF -DLIBXML2_WITH_TESTS=OFF -DLIBXML2_WITH_ZLIB=OFF
 cmake --build libxml2/build.libavif --config Release --parallel